The invention described herein relates to image sensor systems. In particular, the invention relates to image sensor architectures incorporating programmable logic devices together with image sensors on a single semiconductor chip.
The present invention relates to improvements in digital camera technology. Digital camera technology is a rapidly growing field with expanding commercial viability. Digital cameras focus the light from optical images onto image sensors which convert the light into electrical signals that correspond to the optical image. Conventional digital camera technologies utilize charged-coupled devices (CCD) or complementary Metal-Oxide semiconductors (CMOS) to detect light and thereby create digital images. Such CCD or CMOS photosensors translate received light into electronic charging signals that are digitized and processed by a digital camera to produce a digitally storable image. Additionally, color images can be created. For example, red, green, and blue filters allow light to be sampled in each separate spectrum. By combining and evaluating the various data collected in each spectrum, a color image can be created.
Unfortunately, one of the drawbacks of such digital camera technology is that it is as yet unable to obtain the same degree of resolution currently possible with conventional chemically based photographic techniques. Conventional film technologies, which are limited only by the granularity of the chemically based film, generally have a resolution measured in the tens of millions of pixels. In contrast, image sensors currently used in most commercially viable digital cameras feature resolutions of slightly more than one or two million pixels.
Additionally, digital photography suffers from a limited dynamic range. Frequently, the dynamic range of the image sensors used in digital photography is not as wide as that obtainable by conventional chemically based photographic techniques. Often the dynamic range of a digital image sensor is not wide enough to capture scenes having both highlights and dark shadows. This is especially problematic in CMOS based image sensors which, in general, have lower dynamic range than CCD""s.
There are many applications for image sensors, each requiring different auxiliary supporting circuits to operate hence demanding various interface or functions from the image sensors. Designers of the image sensors are burdened with various requirements from the different auxiliary supporting circuits. Thus, there is a need for image sensors which incorporate these varying interfaces or functions on a single integrated circuit (i.e., on a common substrate). Furthermore, there is a need for an image sensor that can be adapted to a wide range of functional parameters or configurations. In particular, there is a need for image sensors which incorporate these and other functionalities all on a single substrate along with a digital pixel array.
In accordance with the principles of the present invention, a single-chip digital image sensor embodiment comprises a digital sensor array having a plurality of pixel sensors for outputting analog signals representing at least one image and having supporting circuitry for receiving and converting the analog signals to digital image information and a programmable logic structure, the programmable logic structure being programmable to provide additional logic and routing for use with said digital sensor array.
A further image sensor embodiment comprises a substrate having a digital sensor array formed thereon. The digital sensor array has a plurality of digital pixel sensors for outputting analog signals representing at least one image and includes supporting circuitry for receiving and converting the analog signals to digital signals. Additionally, the substrate has at least one programmable logic structure formed thereon.
In another embodiment, an image sensor comprises a substrate having formed thereon a digital sensor array, wherein the digital sensor array is formed using CMOS processes. The digital sensor array includes a plurality of light sensitive digital pixel sensors, which output analog signals corresponding to an image, and having supporting circuitry for converting the analog signals to digital signals corresponding to the image. Additionally, the substrate has formed, by CMOS processes thereon, decoder circuitry which receives the digital signals from the digital sensor array and converts the digital signals to adjusted digital values representative of the light intensity impinging upon the plurality of light sensitive digital pixel sensors. The image sensor further includes a plurality of filters which receive the adjusted digital values from the decoder circuitry and from at least one memory. The at least one memory stores the digital values provided by the filters, and the at least one memory is formed on the substrate using CMOS processes. The image sensor also includes a control circuit which selectively transfers the digital values from the plurality of filters to memory addresses within the at least one memory, the control circuit being formed on the substrate using CMOS processes. The image sensor also including the at least one programmable logic structure. The programmable logic structure is formed on the substrate using CMOS processes. Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.